Start implementing LoanPay transaction

include/xrpl/protocol/detail/transactions.macro

@@ -776,7 +776,6 @@ TRANSACTION(ttLOAN_DRAW, 81, LoanDraw, noPriv, ({
     {sfAmount, soeREQUIRED, soeMPTSupported},
 }))
 
-#if 0
 /** The Borrower uses this transaction to make a Payment on the Loan. */
 #if TRANSACTION_INCLUDE
 #   include <xrpld/app/tx/detail/LoanPay.h>
@@ -785,7 +784,6 @@ TRANSACTION(ttLOAN_PAY, 82, LoanPay, noPriv, ({
     {sfLoanID, soeREQUIRED},
     {sfAmount, soeREQUIRED, soeMPTSupported},
 }))
-#endif
 
 /** This system-generated transaction type is used to update the status of the various amendments.
 

src/test/app/Loan_test.cpp

@@ -159,7 +159,7 @@ class Loan_test : public beast::unit_test::suite
             {
                 TenthBips16 const managementFeeRate{
                     brokerSle->at(sfManagementFeeRate)};
-                auto const loanInterest = LoanInterestOutstandingToVault(
+                auto const loanInterest = LoanInterestOutstandingMinusFee(
                     broker.asset,
                     principalOutstanding,
                     interestRate,
@@ -261,7 +261,7 @@ class Loan_test : public beast::unit_test::suite
                             env.test.BEAST_EXPECT(
                                 vaultSle->at(sfLossUnrealized) ==
                                 principalOutstanding +
-                                    LoanInterestOutstandingToVault(
+                                    LoanInterestOutstandingMinusFee(
                                         broker.asset,
                                         principalOutstanding,
                                         interestRate,

src/xrpld/app/misc/LendingHelpers.h

@@ -20,6 +20,8 @@
 #ifndef RIPPLE_APP_MISC_LENDINGHELPERS_H_INCLUDED
 #define RIPPLE_APP_MISC_LENDINGHELPERS_H_INCLUDED
 
+#include <xrpld/ledger/ApplyView.h>
+
 #include <xrpl/basics/Number.h>
 #include <xrpl/protocol/Asset.h>
 #include <xrpl/protocol/Feature.h>
@@ -31,21 +33,22 @@ struct PreflightContext;
 
 // Lending protocol has dependencies, so capture them here.
 bool
-LendingProtocolEnabled(PreflightContext const& ctx);
+lendingProtocolEnabled(PreflightContext const& ctx);
 
 namespace detail {
 // These functions should rarely be used directly. More often, the ultimate
 // result needs to be roundToAsset'd.
 
-Number
+struct LoanPaymentParts
-LoanPeriodicRate(TenthBips32 interestRate, std::uint32_t paymentInterval);
+{
+    Number principalPaid;
+    Number interestPaid;
+    Number valueChange;
+    Number feePaid;
+};
 
 Number
-LoanPeriodicPayment(
+LoanPeriodicRate(TenthBips32 interestRate, std::uint32_t paymentInterval);
-    Number principalOutstanding,
-    TenthBips32 interestRate,
-    std::uint32_t paymentInterval,
-    std::uint32_t paymentsRemaining);
 
 Number
 LoanTotalValueOutstanding(
@@ -61,27 +64,110 @@ LoanTotalInterestOutstanding(
     std::uint32_t paymentInterval,
     std::uint32_t paymentsRemaining);
 
+Number
+LoanPeriodicPayment(
+    Number principalOutstanding,
+    TenthBips32 interestRate,
+    std::uint32_t paymentInterval,
+    std::uint32_t paymentsRemaining);
+
+Number
+LoanLatePaymentInterest(
+    Number principalOutstanding,
+    TenthBips32 lateInterestRate,
+    NetClock::time_point parentCloseTime,
+    std::uint32_t startDate,
+    std::uint32_t prevPaymentDate);
+
+LoanPaymentParts
+LoanComputePaymentParts(ApplyView& view, SLE::ref loan);
+
 }  // namespace detail
 
 template <AssetType A>
 Number
-LoanInterestOutstandingToVault(
+MinusFee(A const& asset, Number value, TenthBips32 managementFeeRate)
+{
+    return roundToAsset(
+        asset, tenthBipsOfValue(value, tenthBipsPerUnity - managementFeeRate));
+}
+
+template <AssetType A>
+Number
+LoanInterestOutstandingMinusFee(
     A const& asset,
     Number principalOutstanding,
     TenthBips32 interestRate,
     std::uint32_t paymentInterval,
     std::uint32_t paymentsRemaining,
     TenthBips32 managementFeeRate)
+{
+    return MinusFee(
+        asset,
+        detail::LoanTotalInterestOutstanding(
+            principalOutstanding,
+            interestRate,
+            paymentInterval,
+            paymentsRemaining),
+        managementFeeRate);
+}
+
+template <AssetType A>
+Number
+LoanPeriodicPayment(
+    A const& asset,
+    Number principalOutstanding,
+    TenthBips32 interestRate,
+    std::uint32_t paymentInterval,
+    std::uint32_t paymentsRemaining)
 {
     return roundToAsset(
         asset,
-        tenthBipsOfValue(
+        detail::LoanPeriodicPayment(
-            detail::LoanTotalInterestOutstanding(
+            principalOutstanding,
-                principalOutstanding,
+            interestRate,
-                interestRate,
+            paymentInterval,
-                paymentInterval,
+            paymentsRemaining));
-                paymentsRemaining),
+}
-            tenthBipsPerUnity - managementFeeRate));
+
+template <AssetType A>
+Number
+LoanLatePaymentInterest(
+    A const& asset,
+    Number principalOutstanding,
+    TenthBips32 lateInterestRate,
+    NetClock::time_point parentCloseTime,
+    std::uint32_t startDate,
+    std::uint32_t prevPaymentDate)
+{
+    return roundToAsset(
+        asset,
+        detail::LoanLatePaymentInterest(
+            principalOutstanding,
+            lateInterestRate,
+            parentCloseTime,
+            startDate,
+            prevPaymentDate));
+}
+
+struct LoanPaymentParts
+{
+    STAmount principalPaid;
+    STAmount interestPaid;
+    STAmount valueChange;
+    STAmount feePaid;
+};
+
+template <AssetType A>
+LoanPaymentParts
+LoanComputePaymentParts(A const& asset, ApplyView& view, SLE::ref loan)
+{
+    auto const parts = detail::LoanComputePaymentParts(view, loan);
+    return LoanPaymentParts{
+        roundToAsset(asset, parts.principalPaid),
+        roundToAsset(asset, parts.interestPaid),
+        roundToAsset(asset, parts.valueChange),
+        roundToAsset(asset, parts.feePaid)};
 }
 
 }  // namespace ripple

src/xrpld/app/misc/detail/LendingHelpers.cpp

@@ -21,13 +21,15 @@
 //
 #include <xrpld/app/tx/detail/Transactor.h>
 #include <xrpld/app/tx/detail/VaultCreate.h>
+#include <xrpld/ledger/View.h>
 
 #include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/st.h>
 
 namespace ripple {
 
 bool
-LendingProtocolEnabled(PreflightContext const& ctx)
+lendingProtocolEnabled(PreflightContext const& ctx)
 {
     return ctx.rules.enabled(featureLendingProtocol) &&
         VaultCreate::isEnabled(ctx);
@@ -44,24 +46,6 @@ LoanPeriodicRate(TenthBips32 interestRate, std::uint32_t paymentInterval)
         (365 * 24 * 60 * 60);
 }
 
-Number
-LoanPeriodicPayment(
-    Number principalOutstanding,
-    TenthBips32 interestRate,
-    std::uint32_t paymentInterval,
-    std::uint32_t paymentsRemaining)
-{
-    if (principalOutstanding == 0 || paymentsRemaining == 0)
-        return 0;
-    Number const periodicRate = LoanPeriodicRate(interestRate, paymentInterval);
-
-    // TODO: Need a better name
-    Number const timeFactor = power(1 + periodicRate, paymentsRemaining);
-
-    return principalOutstanding * (periodicRate * timeFactor) /
-        (timeFactor - 1);
-}
-
 Number
 LoanTotalValueOutstanding(
     Number principalOutstanding,
@@ -92,6 +76,216 @@ LoanTotalInterestOutstanding(
         principalOutstanding;
 }
 
+Number
+LoanPeriodicPayment(
+    Number principalOutstanding,
+    Number periodicRate,
+    std::uint32_t paymentsRemaining)
+{
+    // TODO: Need a better name
+    Number const timeFactor = power(1 + periodicRate, paymentsRemaining);
+
+    return principalOutstanding * (periodicRate * timeFactor) /
+        (timeFactor - 1);
+}
+
+Number
+LoanPeriodicPayment(
+    Number principalOutstanding,
+    TenthBips32 interestRate,
+    std::uint32_t paymentInterval,
+    std::uint32_t paymentsRemaining)
+{
+    if (principalOutstanding == 0 || paymentsRemaining == 0)
+        return 0;
+    Number const periodicRate = LoanPeriodicRate(interestRate, paymentInterval);
+
+    return LoanPeriodicPayment(
+        principalOutstanding, periodicRate, paymentsRemaining);
+}
+
+Number
+LoanLatePaymentInterest(
+    Number principalOutstanding,
+    TenthBips32 lateInterestRate,
+    NetClock::time_point parentCloseTime,
+    std::uint32_t startDate,
+    std::uint32_t prevPaymentDate)
+{
+    auto const lastPaymentDate = std::max(prevPaymentDate, startDate);
+
+    auto const secondsSinceLastPayment =
+        parentCloseTime.time_since_epoch().count() - lastPaymentDate;
+
+    auto const rate =
+        LoanPeriodicRate(lateInterestRate, secondsSinceLastPayment);
+
+    return principalOutstanding * rate;
+}
+
+Number
+LoanAccruedInterest(
+    Number principalOutstanding,
+    TenthBips32 periodicRate,
+    NetClock::time_point parentCloseTime,
+    std::uint32_t startDate,
+    std::uint32_t prevPaymentDate,
+    std::uint32_t paymentInterval)
+{
+    auto const lastPaymentDate = std::max(prevPaymentDate, startDate);
+
+    auto const secondsSinceLastPayment =
+        parentCloseTime.time_since_epoch().count() - lastPaymentDate;
+
+    return tenthBipsOfValue(
+               principalOutstanding * secondsSinceLastPayment, periodicRate) /
+        paymentInterval;
+}
+
+LoanPaymentParts
+LoanComputePaymentParts(ApplyView& view, SLE::ref loan)
+{
+    Number const principalOutstanding = loan->at(sfPrincipalOutstanding);
+
+    TenthBips32 const interestRate{loan->at(sfInterestRate)};
+    TenthBips32 const lateInterestRate{loan->at(sfLateInterestRate)};
+    TenthBips32 const closeInterestRate{loan->at(sfCloseInterestRate)};
+
+    Number const latePaymentFee = loan->at(sfLatePaymentFee);
+    Number const closePaymentFee = loan->at(sfClosePaymentFee);
+
+    std::uint32_t const paymentInterval = loan->at(sfPaymentInterval);
+    std::uint32_t const paymentRemaining = loan->at(sfPaymentRemaining);
+
+    std::uint32_t const prevPaymentDate = loan->at(sfPreviousPaymentDate);
+    std::uint32_t const startDate = loan->at(sfStartDate);
+    std::uint32_t const nextDueDate = loan->at(sfNextPaymentDueDate);
+
+    // Compute the normal periodic rate, payment, etc.
+    // We'll need it in the remaining calculations
+    Number const periodicRate = LoanPeriodicRate(interestRate, paymentInterval);
+    Number const periodicPaymentAmount = LoanPeriodicPayment(
+        principalOutstanding, periodicRate, paymentRemaining);
+    Number const periodicInterest = principalOutstanding * periodicRate;
+    Number const periodicPrincipal = periodicPaymentAmount - periodicInterest;
+
+    // the payment is late
+    if (hasExpired(view, nextDueDate))
+    {
+        auto const latePaymentInterest = LoanLatePaymentInterest(
+            principalOutstanding,
+            lateInterestRate,
+            view.parentCloseTime(),
+            startDate,
+            prevPaymentDate);
+        auto const latePaymentAmount =
+            periodicPaymentAmount + latePaymentInterest + latePaymentFee;
+
+        loan->at(sfPaymentRemaining) -= 1;
+        // A single payment always pays the same amount of principal. Only the
+        // interest and fees are extra
+        loan->at(sfPrincipalOutstanding) -= periodicPrincipal;
+
+        // Make sure this does an assignment
+        loan->at(sfPreviousPaymentDate) = loan->at(sfNextPaymentDueDate);
+        loan->at(sfNextPaymentDueDate) += paymentInterval;
+
+        // A late payment increases the value of the loan by the difference
+        // between periodic and late payment interest
+        return {
+            periodicPrincipal,
+            latePaymentInterest + periodicInterest,
+            latePaymentInterest,
+            latePaymentFee};
+    }
+
+    auto const accruedInterest = LoanAccruedInterest(
+        principalOutstanding,
+        interestRate,
+        view.parentCloseTime(),
+        startDate,
+        prevPaymentDate,
+        paymentInterval);
+    auto const prepaymentPenalty =
+        tenthBipsOfValue(principalOutstanding, closeInterestRate);
+
+    assert(0);
+    return {0, 0, 0, 0};
+    /*
+function make_payment(amount, current_time) -> (principal_paid, interest_paid,
+value_change, fee_paid): if loan.payments_remaining is 0 ||
+loan.principal_outstanding is 0 { return "loan complete" error
+    }
+
+    .....
+
+    let full_payment = loan.compute_full_payment(current_time)
+
+    // if the payment is equal or higher than full payment amount
+    // and there is more than one payment remaining, make a full payment
+    if amount >= full_payment && loan.payments_remaining > 1 {
+        loan.payments_remaining = 0
+        loan.principal_outstanding = 0
+
+        // A full payment decreases the value of the loan by the difference
+between the interest paid and the expected outstanding interest return
+(full_payment.principal, full_payment.interest, full_payment.interest -
+loan.compute_current_value().interest, full_payment.fee)
+    }
+
+    // if the payment is not late nor if it's a full payment, then it must be a
+periodic once
+
+    let periodic_payment = loan.compute_periodic_payment()
+
+    let full_periodic_payments = floor(amount / periodic_payment)
+    if full_periodic_payments < 1 {
+        return "insufficient amount paid" error
+    }
+
+    loan.payments_remaining -= full_periodic_payments
+    loan.next_payment_due_date = loan.next_payment_due_date +
+loan.payment_interval * full_periodic_payments loan.last_payment_date =
+loan.next_payment_due_date - loan.payment_interval
+
+
+    let total_principal_paid = 0
+    let total_interest_paid = 0
+    let loan_value_change = 0
+    let total_fee_paid = loan.service_fee * full_periodic_payments
+
+    while full_periodic_payments > 0 {
+        total_principal_paid += periodic_payment.principal
+        total_interest_paid += periodic_payment.interest
+        periodic_payment = loan.compute_periodic_payment()
+        full_periodic_payments -= 1
+    }
+
+    loan.principal_outstanding -= total_principal_paid
+
+    let overpayment = min(loan.principal_outstanding, amount % periodic_payment)
+    if overpayment > 0 && is_set(lsfOverpayment) {
+        let interest_portion = overpayment * loan.overpayment_interest_rate
+        let fee_portion = overpayment * loan.overpayment_fee
+        let remainder = overpayment - interest_portion - fee_portion
+
+        total_principal_paid += remainder
+        total_interest_paid += interest_portion
+        total_fee_paid += fee_portion
+
+        let current_value = loan.compute_current_value()
+        loan.principal_outstanding -= remainder
+        let new_value = loan.compute_current_value()
+
+        loan_value_change = (new_value.interest - current_value.interest) +
+interest_portion
+    }
+
+    return (total_principal_paid, total_interest_paid, loan_value_change,
+total_fee_paid)
+    */
+}
+
 }  // namespace detail
 
 }  // namespace ripple

src/xrpld/app/tx/detail/LoanBrokerCoverDeposit.cpp

@@ -45,7 +45,7 @@ namespace ripple {
 bool
 LoanBrokerCoverDeposit::isEnabled(PreflightContext const& ctx)
 {
-    return LendingProtocolEnabled(ctx);
+    return lendingProtocolEnabled(ctx);
 }
 
 NotTEC

src/xrpld/app/tx/detail/LoanBrokerCoverWithdraw.cpp

@@ -45,7 +45,7 @@ namespace ripple {
 bool
 LoanBrokerCoverWithdraw::isEnabled(PreflightContext const& ctx)
 {
-    return LendingProtocolEnabled(ctx);
+    return lendingProtocolEnabled(ctx);
 }
 
 NotTEC

src/xrpld/app/tx/detail/LoanBrokerDelete.cpp

@@ -45,7 +45,7 @@ namespace ripple {
 bool
 LoanBrokerDelete::isEnabled(PreflightContext const& ctx)
 {
-    return LendingProtocolEnabled(ctx);
+    return lendingProtocolEnabled(ctx);
 }
 
 NotTEC

src/xrpld/app/tx/detail/LoanBrokerSet.cpp

@@ -48,7 +48,7 @@ namespace ripple {
 bool
 LoanBrokerSet::isEnabled(PreflightContext const& ctx)
 {
-    return LendingProtocolEnabled(ctx);
+    return lendingProtocolEnabled(ctx);
 }
 
 NotTEC

src/xrpld/app/tx/detail/LoanDelete.cpp

@@ -47,7 +47,7 @@ namespace ripple {
 bool
 LoanDelete::isEnabled(PreflightContext const& ctx)
 {
-    return LendingProtocolEnabled(ctx);
+    return lendingProtocolEnabled(ctx);
 }
 
 NotTEC

src/xrpld/app/tx/detail/LoanDraw.cpp

@@ -47,7 +47,7 @@ namespace ripple {
 bool
 LoanDraw::isEnabled(PreflightContext const& ctx)
 {
-    return LendingProtocolEnabled(ctx);
+    return lendingProtocolEnabled(ctx);
 }
 
 NotTEC

src/xrpld/app/tx/detail/LoanManage.cpp

@@ -48,7 +48,7 @@ namespace ripple {
 bool
 LoanManage::isEnabled(PreflightContext const& ctx)
 {
-    return LendingProtocolEnabled(ctx);
+    return lendingProtocolEnabled(ctx);
 }
 
 std::uint32_t
@@ -377,7 +377,7 @@ LoanManage::doApply()
     TenthBips32 const managementFeeRate{brokerSle->at(sfManagementFeeRate)};
     auto const paymentInterval = loanSle->at(sfPaymentInterval);
     auto const paymentsRemaining = loanSle->at(sfPaymentRemaining);
-    auto const interestOutstanding = LoanInterestOutstandingToVault(
+    auto const interestOutstanding = LoanInterestOutstandingMinusFee(
         vaultAsset,
         principalOutstanding.value(),
         interestRate,

src/xrpld/app/tx/detail/LoanPay.cpp

@@ -0,0 +1,228 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2025 Ripple Labs Inc.
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <xrpld/app/tx/detail/LoanPay.h>
+//
+#include <xrpld/app/misc/LendingHelpers.h>
+#include <xrpld/ledger/ApplyView.h>
+#include <xrpld/ledger/View.h>
+
+#include <xrpl/basics/Log.h>
+#include <xrpl/basics/Number.h>
+#include <xrpl/basics/chrono.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/beast/utility/instrumentation.h>
+#include <xrpl/protocol/AccountID.h>
+#include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/Indexes.h>
+#include <xrpl/protocol/Protocol.h>
+#include <xrpl/protocol/PublicKey.h>
+#include <xrpl/protocol/SField.h>
+#include <xrpl/protocol/STAmount.h>
+#include <xrpl/protocol/STNumber.h>
+#include <xrpl/protocol/STObject.h>
+#include <xrpl/protocol/STXChainBridge.h>
+#include <xrpl/protocol/TER.h>
+#include <xrpl/protocol/TxFlags.h>
+#include <xrpl/protocol/XRPAmount.h>
+
+namespace ripple {
+
+bool
+LoanPay::isEnabled(PreflightContext const& ctx)
+{
+    return lendingProtocolEnabled(ctx);
+}
+
+NotTEC
+LoanPay::doPreflight(PreflightContext const& ctx)
+{
+    if (ctx.tx[sfLoanID] == beast::zero)
+        return temINVALID;
+
+    if (ctx.tx[sfAmount] <= beast::zero)
+        return temBAD_AMOUNT;
+
+    return tesSUCCESS;
+}
+
+TER
+LoanPay::preclaim(PreclaimContext const& ctx)
+{
+    auto const& tx = ctx.tx;
+
+    auto const account = tx[sfAccount];
+    auto const loanID = tx[sfLoanID];
+    auto const amount = tx[sfAmount];
+
+    auto const loanSle = ctx.view.read(keylet::loan(loanID));
+    if (!loanSle)
+    {
+        JLOG(ctx.j.warn()) << "Loan does not exist.";
+        return tecNO_ENTRY;
+    }
+
+    auto const principalOutstanding = loanSle->at(sfPrincipalOutstanding);
+    TenthBips32 const interestRate{loanSle->at(sfInterestRate)};
+    auto const paymentInterval = loanSle->at(sfPaymentInterval);
+    auto const paymentRemaining = loanSle->at(sfPaymentRemaining);
+    TenthBips32 const lateInterestRate{loanSle->at(sfLateInterestRate)};
+    auto const latePaymentFee = loanSle->at(sfLatePaymentFee);
+    auto const prevPaymentDate = loanSle->at(sfPreviousPaymentDate);
+    auto const startDate = loanSle->at(sfStartDate);
+    auto const nextDueDate = loanSle->at(sfNextPaymentDueDate);
+
+    if (loanSle->at(sfBorrower) != account)
+    {
+        JLOG(ctx.j.warn()) << "Loan does not belong to the account.";
+        return tecNO_PERMISSION;
+    }
+
+    if (!hasExpired(ctx.view, startDate))
+    {
+        JLOG(ctx.j.warn()) << "Loan has not started yet.";
+        return tecTOO_SOON;
+    }
+
+    if (paymentRemaining == 0 || principalOutstanding == 0)
+    {
+        JLOG(ctx.j.warn()) << "Loan is already paid off.";
+        return tecKILLED;
+    }
+
+    auto const loanBrokerID = loanSle->at(sfLoanBrokerID);
+    auto const loanBrokerSle = ctx.view.read(keylet::loanbroker(loanBrokerID));
+    if (!loanBrokerSle)
+    {
+        // This should be impossible
+        // LCOV_EXCL_START
+        JLOG(ctx.j.fatal()) << "LoanBroker does not exist.";
+        return tefBAD_LEDGER;
+        // LCOV_EXCL_STOP
+    }
+    auto const brokerPseudoAccount = loanBrokerSle->at(sfAccount);
+    auto const vaultID = loanBrokerSle->at(sfVaultID);
+    auto const vaultSle = ctx.view.read(keylet::vault(vaultID));
+    if (!vaultSle)
+    {
+        // This should be impossible
+        // LCOV_EXCL_START
+        JLOG(ctx.j.fatal()) << "Vault does not exist.";
+        return tefBAD_LEDGER;
+        // LCOV_EXCL_STOP
+    }
+    auto const asset = vaultSle->at(sfAsset);
+
+    if (amount.asset() != asset)
+    {
+        JLOG(ctx.j.warn()) << "Loan amount does not match the Vault asset.";
+        return tecWRONG_ASSET;
+    }
+
+    if (isFrozen(ctx.view, brokerPseudoAccount, asset))
+    {
+        JLOG(ctx.j.warn()) << "Loan Broker pseudo-account is frozen.";
+        return asset.holds<Issue>() ? tecFROZEN : tecLOCKED;
+    }
+    if (asset.holds<Issue>())
+    {
+        auto const issue = asset.get<Issue>();
+        if (isDeepFrozen(ctx.view, account, issue.currency, issue.account))
+        {
+            JLOG(ctx.j.warn()) << "Borrower account is frozen.";
+            return tecFROZEN;
+        }
+    }
+
+    auto const periodicPaymentAmount = LoanPeriodicPayment(
+        asset,
+        principalOutstanding,
+        interestRate,
+        paymentInterval,
+        paymentRemaining);
+
+    if (hasExpired(ctx.view, nextDueDate))
+    {
+        // Need to pay the late payment amount
+        auto const latePaymentInterest = LoanLatePaymentInterest(
+            asset,
+            principalOutstanding,
+            lateInterestRate,
+            ctx.view.parentCloseTime(),
+            startDate,
+            prevPaymentDate);
+        auto const latePaymentAmount =
+            periodicPaymentAmount + latePaymentInterest + latePaymentFee;
+        if (amount < latePaymentAmount)
+        {
+            JLOG(ctx.j.warn())
+                << "Late loan payment amount is insufficient. Due: "
+                << latePaymentAmount << ", paid: " << amount;
+            return tecINSUFFICIENT_PAYMENT;
+        }
+    }
+    else if (amount < periodicPaymentAmount)
+    {
+        // Need to pay the regular payment amount
+        JLOG(ctx.j.warn())
+            << "Periodic loan payment amount is insufficient. Due: "
+            << periodicPaymentAmount << ", paid: " << amount;
+        return tecINSUFFICIENT_PAYMENT;
+    }
+
+    return tesSUCCESS;
+}
+
+TER
+LoanPay::doApply()
+{
+    auto const& tx = ctx_.tx;
+    auto& view = ctx_.view();
+
+    auto const amount = tx[sfAmount];
+
+    auto const loanID = tx[sfLoanID];
+    auto const loanSle = view.peek(keylet::loan(loanID));
+    if (!loanSle)
+        return tefBAD_LEDGER;  // LCOV_EXCL_LINE
+
+    auto const brokerID = loanSle->at(sfLoanBrokerID);
+    auto const brokerSle = view.peek(keylet::loanbroker(brokerID));
+    if (!brokerSle)
+        return tefBAD_LEDGER;  // LCOV_EXCL_LINE
+    auto const brokerPseudoAccount = brokerSle->at(sfAccount);
+
+    if (auto const ter = accountSend(
+            view,
+            brokerPseudoAccount,
+            account_,
+            amount,
+            j_,
+            WaiveTransferFee::Yes))
+        return ter;
+
+    loanSle->at(sfAssetsAvailable) -= amount;
+    view.update(loanSle);
+
+    return tesSUCCESS;
+}
+
+//------------------------------------------------------------------------------
+
+}  // namespace ripple

src/xrpld/app/tx/detail/LoanPay.h

@@ -0,0 +1,53 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2025 Ripple Labs Inc.
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#ifndef RIPPLE_TX_LOANPAY_H_INCLUDED
+#define RIPPLE_TX_LOANPAY_H_INCLUDED
+
+#include <xrpld/app/tx/detail/Transactor.h>
+
+namespace ripple {
+
+class LoanPay : public Transactor
+{
+public:
+    static constexpr ConsequencesFactoryType ConsequencesFactory{Normal};
+
+    explicit LoanPay(ApplyContext& ctx) : Transactor(ctx)
+    {
+    }
+
+    static bool
+    isEnabled(PreflightContext const& ctx);
+
+    static NotTEC
+    doPreflight(PreflightContext const& ctx);
+
+    static TER
+    preclaim(PreclaimContext const& ctx);
+
+    TER
+    doApply() override;
+};
+
+//------------------------------------------------------------------------------
+
+}  // namespace ripple
+
+#endif

src/xrpld/app/tx/detail/LoanSet.cpp

@@ -49,7 +49,7 @@ namespace ripple {
 bool
 LoanSet::isEnabled(PreflightContext const& ctx)
 {
-    return LendingProtocolEnabled(ctx);
+    return lendingProtocolEnabled(ctx);
 }
 
 std::uint32_t
@@ -359,7 +359,7 @@ LoanSet::doApply()
     TenthBips32 const managementFeeRate{brokerSle->at(sfManagementFeeRate)};
     // The portion of the loan interest that will go to the vault (total
     // interest minus the management fee)
-    auto const loanInterestToVault = LoanInterestOutstandingToVault(
+    auto const loanInterestToVault = LoanInterestOutstandingMinusFee(
         vaultAsset,
         principalRequested,
         interestRate,